Ahmed Zewail, who died recently, was the Nobel Laureate in which field?

Prof. Ahmed Zewail (70), Egyptian Chemist and Nobel Laureate, has recently passed away in United States. Zewail won the Nobel Chemistry Prize in 1999 for his pioneering work in femtochemistry, the study of chemical reactions in ultra-short time scales. He was professor at the California Institute of Technology and a Science Advisor to President Barack Obama and was the first Arab scientist to win the Nobel Prize.